Stereoscopic cinematography



June 21, 1932. E, P, 1 LE BARBIER STEREOSCOPIC CINEMATOGRAPHY Filed Feb.5, 192'9 3 Sheets-Sheet 2 June 21, .1932.4 E. P. l.. LE BARBIERSTEREOSCOPI GINEMATOGBAPHY Filed Feb. 5, 1929 3 Sheets-Sheet 3 PatentedJune 21, 1932.l

PATENT OFFICE SMILE PIERRE LOUI LE BARBIER, F NICE, FRANCE ysrnmzoscorxc cnn::nm'roaanrrrry Application led February `li., 1929,Serial No. 837,687, and in Belgium March 30, 1928.

The present invention relates to stereosc opc photography and, moreparticularly, to the application of the stereoscopic priuciple to theproduction of moving pictures.A f One ofthe objects of the invention isto y provide a method and apparatus for produclng enlar ed stereoscopicimages ofv objects correspon ing substantially to those observed by thehuman eye. Another object is to provide means for registering right andleft stereoscopic images on the same stri of film.

Further o jects will appear in the course ofthe detailed description nowtov be given with nreference to the accompanying drawings, in which ig.1 is a diagram showing the relative positions of the object and one formof aparatus constructed in accordance with the invention;

Fig. 2 is a similar diagram showing the positions that would be occupiedby the same object relatively to the ordinary types ofstereocinematographic apparatus now in 85 use;

Fig. 3 is a diagram showing the position which the object occupiesrelatively to a second constructive embodiment of theinvenj tion;

3 0 Fig. 4 is a diagramlshowing the position that the object representedin Fig. 3 would occupy relatively to an ordinary stereocinematographicapparatus; A

Fig. 5 is a plan of an apparatus embodying theprinciple of the devicesillustrated diagrammatically in Figs'. 1 and'3;

` Fig. 6 represents, in elevation, the position of lhe lm relativelytothe apparatus shown in i 5; Figgs. 7 and '8 are elevations and plans,respectively of the apparatus illustrated in Fig. 5,- showing all theessential constructive details thereof. In the stereoscopic systemsemployed up to maintain the two objectives used for taking -.the pictureand for projecting at a fixed distance corresponding approximately vtothatl of thehuman eyes i. e. 60-70 millimeters,

generally in the vicinity of 63 millimeters.

the present time, it .has been the custom to This procedure is perfectlylogical when the negatives are viewed in the ordinary stereoscope, buthas serious defects-where the image being projected is considerablymagnified as in stereocinematography. In order that the impression ofrelief be the same for the spectator in the Acase of a magnified imageas is observed by a pair of normal eyes, it is necessary that thedistance between the objectives be increased in proportion totheirelative size a0 of the real object and the image as received on thescreen. In cinematography, for example, it is common to enlarge theobject in the proportion of `1 2 or 1 3. The distance between theobjectives should, therefore, be 55 twice or three times -70 mm. If thedegree of enlargement of the object be represented by n, the distancebetween*` objectives may be taken as n X 60-70 mm3. The angle ofconvergence of the eyes may be taken'as a 70 measure of the reliefobtained. If, therefore, it be desired to conserve the same relief in anenlarged image, it is necessary to maintain the same angle ofconvergence during projection.

When enlarged projections are made with. objectives 60-70 mm. apart,blurring effects are obtained because of the impossibility of-superposing the edges of each object in the field. With the objectivesin the position above defined this effect is, as will be shown later,done away with.

Figs. 1 and 2 show, diagrammatically, the

differences in relief obtained withl the type of stereoscopic apparatusnow. generally in g5 juse and with an apparatus of the type hereinafterto be described, In both figures the cylinder is assumed to be viewedlaterally by two normal eyes (or objectives) at o and, o1'

ls ituated on line AB. When projected at double enlargement, thecylinder axis C will -rem'ain the same but its radius will be2 r andthedistance between axis C and line AB will be doubled i.- e. at DE. A

In Fig. 1, the objectives, situated at O and vOx 'on line DE are spacedat double the discylinder of radius 2 'r will, therefore, have the sameaspect and present the same relief as the original cylinder and anglewill be equal to angle In the case represented in Fig. 2, the eyes (orobjectives) are at o, o1 but they are spaced at the same distance at O,O1. An le a viewed from O, O1 will be greatly re uced and the magnifiedimage of the cylinder will' lack the relief of the original. Angleembraces a larger sector i. e. is increased by twice the angle y, whilethe oblique portion whose relief is to be reproduced is reduced to 2 8.

The increase of distance between the objectives involves certain chan esin the medium, and back grounds, the luminous rays, in certain cases,crossing behind, or to the left or right, of those of the foreground. Inthis connection it is to be noted that:

1 the visual sensation of relief exists readily only for objects in theforeground, and objects in the medium or back ground are estimated bycomparison with those in the foreground;V

2 normal eyes do not perceive accurately horizontal errors in thespacing of objects the maximum angle of displacement of the eyes intheir orbits being about 85, if the spectator is close to a screen, hewill see accurately only a limited portion thereof, and errors occurringin distant portions will escape him entirely, while, if placed ata disvtance from the same screen, he will view the entire image but will notdetect errors in projection because'of therelatively large spaceintervening between himself and the screen;

3 normal eyes are much more sensitive to yerttsical errors in therepresentation of obleC From the foregoing it follows that, while thedistance between a pair of objectives may be increased safely inhorizontal directions up to ab0ut85 in conjugated and convergent typesof apparatus, the vertical dist ance therebetween should not be altered.

Fig. 4represents,diagrammaticall a stereocinematographic apparatus of te type` `now in use. o and o1 are objectives having parallel axes a: yand ai y', and F, F1 a pair of films positioned perpendicularly to thelatter. A c linder having an axis C isrepresented as eing viewedlaterally by the objectives. Each image of the cylinder hasl the form ofa non-symmetrical deformed oval shown in solid lines on the film whichis supposed to be turned into view. In lreality this image is formedbetween two circumferences shown. in dotted lines. The deformation isdiicult to detect in ordinary stereophotography because of the fact thatthe composite image resulting from the superposition of points f and f1is much smaller than the object photographed. In stereocineniatografphy, when the proj ected image is considerably larger than the originalobject, this defect becomes at once apparent and requires correction.

Fig. 3 shows how correction is obtained. Here, the axes of ob'ectives oand o1 are convergent and films F1 are positioned perpendicularly tosaid axes. The images reproduce exactly the real shape of the object,and 'the deformation noted above is done away with. The constructiveembodiment of the invention shown in Figs. 5 to 8 consists of apositioned to receive rays from g, ggf-and a film receivingsimultaneously a pair of juxtaposed images 7', j.

Simultaneous control of arms g, g yand of 'mirrors g2, g2 is obtained bymeans, of a milled disc .(not shown) capable of being manipulated byhand'to rotate a gear m, the latter driving (l) arms g, g simultaneouslyin opposite directions through the intermediary of pinoins n, fn, andworms n', 'n2 mountedon shafts nl, n1, and independent sectors g, gaconnected in driving relation to g, g, and (2) mirror g, g2 through theintermediary of pinions n, n, helicoidal gear q1 mounted on shaft g, apair of gears similar to Y inions n, n driven from shaft q and drivingworms p, p, and concentric gears g, g* attached to each mirror mountedon concentric shafts g, g.

` The various gear systems should be designed so that (1) arms i, g' aredisplaced simultaneously through t e same angle, and (2) mirrors g2, gthrough an angle equal to one-half of thatof each arm.

In proceeding to effect a photographing.

operation, (1) the right hand objective may be focussed on the center ofthe sub'ect, and the left hand image on the ed of e latter 'orconversely, or (2) a combination of these procedures may be employed soas to accentuate one image or the other. To insure accuratesuperposition in projection, the first images may consist sim y ofreference marks i. e. of central vertical or horizontal lines which maybe centered in the manner generally employed in polychrome photog raphy.

What I claim is 1. In combination, a pair of extensible arms rotatableabout a common axis, said arms being rotatable indifferent planes, re-

.ilecting elements supported on said arms, a

lens system, and means for reflecting images Projected by thereflectingelements into'said ens s stem. 2. n combination, a pairy of extensiblearms rotatable about a common axis', said 6 arms being rotatable indifferent planes, re-

fleeting elements mounted on said arms, a lens s stem, means forreflecting images projecte by said reflecting elements into saidl lenssystem, and means for simultaneously 10 displacing said arms throughequal angles.

3. In combination, a pair of extensible arms rotatable about a commonaxis, said arms being rotatable in diierent lanes, refleeting elementssupported by said arms, a .15 lens system, reflecting means interposedbetween said relecting elements vand the lens system and adapted todeflect light rays coming from the former into the latter, and-means4for simultaneously effecting angular dis-vv 20 placement of saidreflecting means and of said arms. p

4. The method of producing stereoscopicl images which comprises the stepof increasing the distance between a pair` of objectives 25 duringphotographic registration beyond 70v millimeters by an amount proortional between the size of the object in photographed and the sizeofthe'image t ereof as projected on a screen. 80- I n" testimony whereofI have signed this specification.

EMILE PIERRE LOUIS .LE BARBIER.

